If the caller chooses to not show their number then it would show no caller ID
Could have what I've got lately, loads of Spam calls and usually they don't want you to know who they are
If you go into your phone app
Tap on the three dots on the top right
Go into settings and go into block numbers
You will see block spam and scam calls
Turn that on and hopefully should cut down on some of it
You can also block unknown and private numbers
